FRANKFURT -- When Volkswagen executives decided in 2006 to use software to evade emissions rules, they needed help. No one inside Volkswagen knew how to write the software.

So the company turned to one of its most trusted partners: the German supplier, Robert Bosch. Working from Volkswagen specifications, Bosch developed code that instructed computers in diesel engines to fully deploy pollution controls only when the cars were being tested in laboratories, according to lawsuits in the Unit